John Martini: The National Park Service historian discusses the forts that once defended San Francisco from an enemy that never came. [7:30 p.m., Conference Center, Building A, Fort Mason Center, S.F.]

‘Healthy Living to 100’: Dr. Harris Meyer shares insights and keys to slowing down the clock and getting the most out of life’s journey. [4:30 p.m., Mission Bay Branch, 960 Fourth St., S.F.]Film screening: Program features a screening of “Prisoner of Her Past,” a documentary about a Holocaust survivor with late-onset post-traumatic stress disorder. [5:45 p.m., Main Library, Koret Auditorium, 100 Larkin St., S.F.]

CITY

California legends: The California Historical Society hosts a gala honoring the founders of Silicon Valley, known as the “Traitorous Eight,” with its 2011 Legends of California Award. [6 p.m., St. Regis hotel, 125 Third St., S.F.]